Vehicle seats may include adjustable head restraints. As an example, U.S. Pat. No. 4,830,434 to Ishida et al. discloses an adjustable head rest device for a vehicle seat. The device includes a head rest body for supporting the head of an occupant of the seat. The device further includes an adjusting member for adjusting the position of the head rest body with respect to the seat continuously within a defined range of movement.
As another example, U.S. Pat. No. 7,316,455 to Metz et al. discloses a locking device and a headrest. The locking device includes spring elements which can be engaged in at least one locking position. The locking device can be displaced in relation to at least two retaining bars that have a number of recesses. The spring elements co-operate with the recesses in such a way that engagement of the spring elements in their locking position locks the locking device in relation to the retaining bars. The spring elements are configured in such as way that the retaining bars are locked by the mechanical fixing of the spring elements in their central zone or by exertion of a force on the spring elements in their central zone.